STOP-Bang Score and Factors Predicting Difficult Intubation for Prediction of Difficult Mask Ventilation in Obese Patients

The goal of this prospective observational study is to test combination of STOP-Bang score and factors predicting difficult intubation can improve accuracy of prediction difficult mask ventilation in obese patients that undergoing to elective surgery under general anesthesia. The main question\[s\] it aims to answer are: * Can combination of STOP-Bang score and factors predicting difficult intubation improve accuracy of prediction difficult mask ventilation in obese patients? * Study about complication after endotracheal tube insertion in obese patients that undergoing to elective surgery under general anesthesia. Participants who undergoing to elective surgery under general anesthesia will * Routine preoperative evaluation and ask about STOP bang questions, evaluate neck circumference, Mallampati grade,Thyromental distance (That routine physical examination for anesthetic care pre-operation) * In operation room, patients will be inducted anesthesia by anesthesiologist (step routine for general anesthesia),observe difficult mask ventilation grading before intubate endotracheal tube and complication after endotracheal tube insertion. If there is a comparison group: Researchers will compare obese patients with/without high STOP bang score \>=3 point plus factor predicting difficult intubation (Mallampati grade 3-4, Neck circumference \> 42 cm, Thyromental distance \< 6 cm)to prediction difficult mask ventilation